1. Field of the Invention
The present invention relates to a resonator used in a bonding apparatus for overlapped bonded members by ultrasonic vibration
2. Description of the Prior Art
As disclosed in Japanese Published Patent Application No. Sho 54-13349, it is known that an ultrasonic vibration bonding apparatus is provided with a resonator connected to an oscillator for generating ultrasonic vibration and a mount for mounting overlapped bonded members thereon and holding these members under pressure between this mount and the resonator, wherein an interface of the overlapped bonded members is bonded by transmitting the ultrasonic vibration from the oscillator to the resonator.
The resonator used in such an ultrasonic vibration bonding apparatus is made through the following process. Materials for the resonator are cut to a shape and size determined by the materials, thickness and shape of the bonded members, oscillation output of the oscillator and the like to make a primarily processed product. The primarily processed product is then connected to the oscillator for actual vibration, and the length and thickness is regulated to have a desired resonance state. A secondary processing including tuning of the resonance state is thus added to the primarily product before official use. However, the bonding function area of the resonator is worn down by diffusion caused by bonding temperature. If the surface profile of the bonding function area of the resonator becomes rough by such repeated wear, a bonding failure of the bonded members may occur or a bonding flaw may be produced on the surface of the bonded members, thereby leading to lack of quality and reliability. To improve the situation, the surface of the bonding function area of the resonator must be polished for repair. However, the resonator must be removed from the apparatus for repair, and reassembling and re-tuning of the resonator require a great deal of labor and time. In addition, a polishing margin of the bonding function area can not be secured sufficiently to obtain an appropriate resonance state. The resonator therefore can not be used any longer after several repairs and quite uneconomical for the user. Also, since the bonding function area is too short to carry out an effective bonding operation on the inside of a workpiece having a box-like shape because the workpiece is quite deep.